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path: root/drivers/tty/tty_ldisc.c
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Diffstat (limited to 'drivers/tty/tty_ldisc.c')
-rw-r--r--drivers/tty/tty_ldisc.c111
1 files changed, 56 insertions, 55 deletions
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 2d822aa259b2..3737f55272d2 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -308,48 +308,66 @@ EXPORT_SYMBOL_GPL(tty_ldisc_deref);
static inline int __lockfunc
-tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout)
+__tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout)
{
return ldsem_down_write(&tty->ldisc_sem, timeout);
}
static inline int __lockfunc
-tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout)
+__tty_ldisc_lock_nested(struct tty_struct *tty, unsigned long timeout)
{
return ldsem_down_write_nested(&tty->ldisc_sem,
LDISC_SEM_OTHER, timeout);
}
-static inline void tty_ldisc_unlock(struct tty_struct *tty)
+static inline void __tty_ldisc_unlock(struct tty_struct *tty)
{
return ldsem_up_write(&tty->ldisc_sem);
}
static int __lockfunc
+tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout)
+{
+ int ret;
+
+ ret = __tty_ldisc_lock(tty, timeout);
+ if (!ret)
+ return -EBUSY;
+ set_bit(TTY_LDISC_HALTED, &tty->flags);
+ return 0;
+}
+
+static void tty_ldisc_unlock(struct tty_struct *tty)
+{
+ clear_bit(TTY_LDISC_HALTED, &tty->flags);
+ __tty_ldisc_unlock(tty);
+}
+
+static int __lockfunc
tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2,
unsigned long timeout)
{
int ret;
if (tty < tty2) {
- ret = tty_ldisc_lock(tty, timeout);
+ ret = __tty_ldisc_lock(tty, timeout);
if (ret) {
- ret = tty_ldisc_lock_nested(tty2, timeout);
+ ret = __tty_ldisc_lock_nested(tty2, timeout);
if (!ret)
- tty_ldisc_unlock(tty);
+ __tty_ldisc_unlock(tty);
}
} else {
/* if this is possible, it has lots of implications */
WARN_ON_ONCE(tty == tty2);
if (tty2 && tty != tty2) {
- ret = tty_ldisc_lock(tty2, timeout);
+ ret = __tty_ldisc_lock(tty2, timeout);
if (ret) {
- ret = tty_ldisc_lock_nested(tty, timeout);
+ ret = __tty_ldisc_lock_nested(tty, timeout);
if (!ret)
- tty_ldisc_unlock(tty2);
+ __tty_ldisc_unlock(tty2);
}
} else
- ret = tty_ldisc_lock(tty, timeout);
+ ret = __tty_ldisc_lock(tty, timeout);
}
if (!ret)
@@ -370,38 +388,26 @@ tty_ldisc_lock_pair(struct tty_struct *tty, struct tty_struct *tty2)
static void __lockfunc tty_ldisc_unlock_pair(struct tty_struct *tty,
struct tty_struct *tty2)
{
- tty_ldisc_unlock(tty);
- if (tty2)
- tty_ldisc_unlock(tty2);
-}
-
-static void __lockfunc tty_ldisc_enable_pair(struct tty_struct *tty,
- struct tty_struct *tty2)
-{
- clear_bit(TTY_LDISC_HALTED, &tty->flags);
+ __tty_ldisc_unlock(tty);
if (tty2)
- clear_bit(TTY_LDISC_HALTED, &tty2->flags);
-
- tty_ldisc_unlock_pair(tty, tty2);
+ __tty_ldisc_unlock(tty2);
}
/**
* tty_ldisc_flush - flush line discipline queue
* @tty: tty
*
- * Flush the line discipline queue (if any) for this tty. If there
- * is no line discipline active this is a no-op.
+ * Flush the line discipline queue (if any) and the tty flip buffers
+ * for this tty.
*/
void tty_ldisc_flush(struct tty_struct *tty)
{
struct tty_ldisc *ld = tty_ldisc_ref(tty);
- if (ld) {
- if (ld->ops->flush_buffer)
- ld->ops->flush_buffer(tty);
+
+ tty_buffer_flush(tty, ld);
+ if (ld)
tty_ldisc_deref(ld);
- }
- tty_buffer_flush(tty);
}
EXPORT_SYMBOL_GPL(tty_ldisc_flush);
@@ -517,15 +523,16 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
{
int retval;
struct tty_ldisc *old_ldisc, *new_ldisc;
- struct tty_struct *o_tty = tty->link;
new_ldisc = tty_ldisc_get(tty, ldisc);
if (IS_ERR(new_ldisc))
return PTR_ERR(new_ldisc);
- retval = tty_ldisc_lock_pair_timeout(tty, o_tty, 5 * HZ);
+ tty_lock(tty);
+ retval = tty_ldisc_lock(tty, 5 * HZ);
if (retval) {
tty_ldisc_put(new_ldisc);
+ tty_unlock(tty);
return retval;
}
@@ -534,19 +541,18 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
*/
if (tty->ldisc->ops->num == ldisc) {
- tty_ldisc_enable_pair(tty, o_tty);
+ tty_ldisc_unlock(tty);
tty_ldisc_put(new_ldisc);
+ tty_unlock(tty);
return 0;
}
old_ldisc = tty->ldisc;
- tty_lock(tty);
- if (test_bit(TTY_HUPPING, &tty->flags) ||
- test_bit(TTY_HUPPED, &tty->flags)) {
+ if (test_bit(TTY_HUPPED, &tty->flags)) {
/* We were raced by the hangup method. It will have stomped
the ldisc data and closed the ldisc down */
- tty_ldisc_enable_pair(tty, o_tty);
+ tty_ldisc_unlock(tty);
tty_ldisc_put(new_ldisc);
tty_unlock(tty);
return -EIO;
@@ -566,8 +572,11 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty_ldisc_restore(tty, old_ldisc);
}
- if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc)
+ if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) {
+ down_read(&tty->termios_rwsem);
tty->ops->set_ldisc(tty);
+ up_read(&tty->termios_rwsem);
+ }
/* At this point we hold a reference to the new ldisc and a
reference to the old ldisc, or we hold two references to
@@ -580,13 +589,11 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
/*
* Allow ldisc referencing to occur again
*/
- tty_ldisc_enable_pair(tty, o_tty);
+ tty_ldisc_unlock(tty);
/* Restart the work queue in case no characters kick it off. Safe if
already running */
schedule_work(&tty->port->buf.work);
- if (o_tty)
- schedule_work(&o_tty->port->buf.work);
tty_unlock(tty);
return retval;
@@ -675,16 +682,13 @@ void tty_ldisc_hangup(struct tty_struct *tty)
wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
wake_up_interruptible_poll(&tty->read_wait, POLLIN);
- tty_unlock(tty);
-
/*
* Shutdown the current line discipline, and reset it to
* N_TTY if need be.
*
* Avoid racing set_ldisc or tty_ldisc_release
*/
- tty_ldisc_lock_pair(tty, tty->link);
- tty_lock(tty);
+ tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT);
if (tty->ldisc) {
@@ -706,7 +710,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
WARN_ON(tty_ldisc_open(tty, tty->ldisc));
}
}
- tty_ldisc_enable_pair(tty, tty->link);
+ tty_ldisc_unlock(tty);
if (reset)
tty_reset_termios(tty);
@@ -758,16 +762,17 @@ static void tty_ldisc_kill(struct tty_struct *tty)
/**
* tty_ldisc_release - release line discipline
- * @tty: tty being shut down
- * @o_tty: pair tty for pty/tty pairs
+ * @tty: tty being shut down (or one end of pty pair)
*
- * Called during the final close of a tty/pty pair in order to shut down
- * the line discpline layer. On exit the ldisc assigned is N_TTY and the
- * ldisc has not been opened.
+ * Called during the final close of a tty or a pty pair in order to shut
+ * down the line discpline layer. On exit, each ldisc assigned is N_TTY and
+ * each ldisc has not been opened.
*/
-void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
+void tty_ldisc_release(struct tty_struct *tty)
{
+ struct tty_struct *o_tty = tty->link;
+
/*
* Shutdown this line discipline. As this is the final close,
* it does not race with the set_ldisc code path.
@@ -776,13 +781,9 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
tty_ldisc_debug(tty, "closing ldisc: %p\n", tty->ldisc);
tty_ldisc_lock_pair(tty, o_tty);
- tty_lock_pair(tty, o_tty);
-
tty_ldisc_kill(tty);
if (o_tty)
tty_ldisc_kill(o_tty);
-
- tty_unlock_pair(tty, o_tty);
tty_ldisc_unlock_pair(tty, o_tty);
/* And the memory resources remaining (buffers, termios) will be
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 10:22:30 +0000